Method of and apparatus for electrically recording and reproducing sound or other vibrations



Feb. 18, 1936. M DUsToN 2,030,93

METHOD OF AND APPARATUS FOR ELECTRICALLY RECORDING AND REPRODUCINGSOUND. OR OTHER VIBRATIONS Original Efild Aug. 13, 1931 4 Sheets-SheetINVENTOR Meri@ Euston ATTORNEYS Feb. 18, 1936. M. DUsToN 2,030,973

METHOD OF AND APPARATUS FOR ELECTRICALLY RECORDING AND REPRODUCING SOUNDOR OTHER VIBRATIONS Original Filed Aug. 13, 1931 4 Sheets-Sheet 2INVENTOR MerI/e Euston BYMMMGX ATTORNEYS Feb.1s,1936. M DUSTON 2,030,973

METHOD OF' AND APPARA'US FOR ELECTRICALLYRECORDING AND REPRODUCING SOUNDOR OTHER VIBRATIONS Original Filed Aug. l5, 193,1 4 Sheets-Sheet 3 lllla .'65v

INVENTOR` Merle Baston ATTORNEYS Feb. 18, 1936. M. Dus'roN 2,030,973

METHOD .OF AND APPARATUS FOR'ELECTRICALLY RECORDING' AND REPRODUINGSOUND OR OTHER VIBRATIONS Original Filed Aug.l 13, 1931 4 Sheets-Sheet 4/454 AlllulullllhwkIIIIIIIIIIIIIIUIHIHII||HIHHI|IIIIHINIIIINHIHIIllllllllIHIIIIIIHIIIIIIIHEIHHIIIIIIIIlllllllllllllllllHIHII|l|llllMmmmINVENTOR Merle Huston, BY

AATTORNEYS Patented Feb. 1s, 193e Y UNlrD STATES ATENT FFHCE MerleDuston, Detroit, Mich.

Application August 13, 1931, Serial No. 556,743 Renewed August 2, 193421 Claims. (Cl. 179-1001) pared tape, without the use of anyintermediate 1 apparatus, such as a device for causing the electriccurrent to Vary the intensity or direction of a. beam of light, as iscommonly used in record-f ing systems at present in use.

An object of my invention is to simplify the recording and reproducingof electric impulses by eliminating the use of light sensitive materialsand any necessity for the delevopment or xation of the same.

Another object of my invention is the elimination of the use of costlyand delicate optical apparatus in the recording system.

Another object of my invention is to simplify and increase theemciencyof the reproduction of the recorded sounds or currents.

Another object' of my invention is to provide a system whereby the samemachine may be used for recording and immediately reproducing therecorded signals for monitoring and other purposes.

A further object of my invention is to provide an apparatus and methodfor recording light waves, sound waves, or other mechanical vibrationsand automatically reproducing therecorded signals after al predeterminedlapse of time.

A further object of my invention is to provide an apparatus in which therecording may be done at one time and the reproducing immediatelythereafter or at any desired subsequent time.

Still another object of my invention is to provide a method andapparatus for recording mechanical vibrations by producing indices on atape and subsequentlytransforming these indices into an accuratereproduction of the mechanical 'vibrations.

Another object of my inventionis to provide a means for recording soundWaves or other mechanical vibrations by producing indices on a tapewhich can be kept for long periods of time without substantialdeterioration.

A further object of my invention is to provide a means for recordinglight impulses, sound waves, or other mechanical vibrations by producingvisual indices on 'a tape which can be immediately used for analyzingthe various frequency characteristics of the vibrations.

` driving the constant speed roller 9 through a Other objects of myinventionlwill be apparent from the following disclosures:

Figure 1 is an assembled View. of a combined recording and reproducingmechanism;

Fig. 2 is a schematic diagram of an amplifier; 5

Fig. 3 is a view, partly in section, taken on line 3--3 of Fig.. l;

Fig. 4 is an elevation of a modified form of recording mechanism;

Fig. 5 is a view, partly in section, taken on line m 5 5 of Fig. 4; i

Fig. 6 is a view of another form of recording mechanism;

Fig. 7 is a side view of the recording arm of Fig. 6;

Fig. 8 is an end view of the recording arm of Fig. 6;

Fig. 9 is a diagram of a battery-operated recording apparatus;

. Fig. 10 is an enlarged view of the recording arm shown in Fig. 1;

Fig. 11 is a section on line II--I I, Fig. 10; and

Fig. 12 shows a fragment of a tape partly used.

A suitable frame I is shown in Fig. 1 on which is'supported a supplyreel 2 and a receiving reel 3. A vtape 4, for receiving marks orindices, carrying a suitable chemical compound (as more fully explainedhereafter) is fed from the supply reel 2 between a xed contact 5 and amovable contact 6 of a recording mechanism A, and then, if it is desiredto immediately reproduce the recorded signals, is lead over an exposureguide I -of the reproducing mechanism C. The tape then passes betweenthe rollers 8 and 9 to the receiving reel 3. t 1 l f A motor I0 isprovided to furnish power and operate preferably through any suitablevariable speed gear reduction II todrive the shaft I2 on which ismounted a. pulley I3. Suitable belts I4 and I5 are driven from a portionof the pulley I3 and pass over pulleys I6 and I1 connected to the shaftsI8 and I9 which carry the reels 2 and 3 respectively, the shafts I6 andI1 being suitably supported in the frame. The crossed driving belt 20receives power from pulley I3 for suitable pulley connection. The motorIII is pref.- erably an electric motor of theconstant speed type but maybe any suitable driving. mechanism.

In order that the tape 4 may be passed at constant speed through theapparatus for recording or reproducing, the tape is driven by theconstant speed roller 9` and the companion roller 8 resiliently mountedto press against the tape. The belt I4 operating between the pulley I3and the receiving reel 3 is so mounted on the pulleys I3 and I6 that itcan slip and only revolves the reel 3 at a suicient rate of speed tokeep a suitable tension on the tapeas it comes from the constant speedrollers 8 and 9. The tension on the tape from the constant speed rollersrevolves reel 2 and unwinds the tape from the reel, but in order to keepa suitable tension on the tape any suitable retarding mechanism may beprovided, and in the mechanism shown the belt I5 is mounted betweenpulleys I3 and I1 so that p it tends to drive the reel in the oppositedirection, but is sufliciently loosely mounted to slip on the pulleysand act as a brake to keep the desired tension on the tape. When thetension of the constant speed rollers is released from the tape,however, the belt I5, which is provided with more tension than the beltI4, will act as a driving belt for rewinding the tapeon the supply reel2, and in this case the belt I4 acts to retard the reel 3 to preservethe desired tension on the tape.

The constant'speed pulley 8 is carried at one end of the arm 2|, whichis rotatably supported on a shaft 22 at the other end. Shaft 22 ismounted on frame I, and a screw tensioning device 23 is also mounted onthe frame for adjusting the arm 2| to secure the desired pressurebetween the rollers 8 and 9 for driving the tape.

In the recording mechanism the fixed contact 5 is mounted on aninsulating panel 25, and is preferably of brass but may be of any goodelectrically conducting material, and is preferably provided with acurved, polished surface 26 to facilitate the passage of the tapethereover and to provide a convex surface.

A movable contact holding arm 21 is mounted for pivotal movement on thepivot member 23 carried by the insulating panel 25. on the arm 21 is abalance weight 29 which may be adjusted along the threaded portion 36lof the contact arm. Carried by the arm 2 is a collar 3l preferably ofinsulating'material. To one side of the collar,`spring 32 is connected,the other end of the spring being carried by adjusting screw 33 whichpasses through an aperture on the threaded stud 34 and is adjustable bymeans of a threaded nut 34a which bears against the stud 34. The stud 34is mounted to the panel 25. A yoke 35 is also carried by the collar 3|,the yoke being provided so that the tape 4 may pass between the sidesthereof without contacting therewith. A stud 36 is similarly carried bythe panel 25 through an aperture in which the screw 31 is passed, thescrew being connected to the yoke 35 by means of a tension spring 38. Anut 39 engages the threaded endA of the screw 31 and bears against thestud 36 so that the screw may be adjusted.

A contact holder 40 is pivotally secured to the free end of the arm 21by means of a screw 4I passing through the members 42 of the contactyholder and arm 21. At the outer end of the contact holder 40 a. slot 52is provided to receive a contact blade 6. Secured to the holder 40 is acap portion 43 in which a set screw 44 is threaded so that the set screwmay be adjusted to clamp the blade 6 tightly in the holder.

An amplifier 45, which may be of the type shown in Fig. 2, is providedwith suitable terminals 46 and 41. From the terminal 46 a lead 56electrically connects terminal 46 to the fixed contact 5. The lead 5Iconnects the terminal 41 through the arm 21 to the movable contact 6.

The contact 6 is preferably a. thin. stift blade Mounted of any goodelectrical conducting material, such as a platinum alloy, steel,phosphor bronze or the like. It should be of such material that it willresist the wear due to the frictional engagement of the tape and whichwill stand up under the action of electrical current, and not be readilyattacked by the chemical compounds carried by the tape.

For recording frequencies within the audible range the blade 6 should beas thin as practicable and still be sufliciently rigid to resistdeformations due to the forces acting thereon by the passing of thetape, and the pressure between it and the xed contact 5. Steel blades asthin as one and one-half mills have been successfully used. As the bladewears it may be adjusted in the slot 52 and reset by the set screw 44 tobe rigidly held in the contact holder` The width of the bladel may varywithin wide limits dependent upon the current density used, theresistance of the tape and the width of record desired for reproductionpurposes. A blade of one-eighth inch width has given good results withthe above described apparatus.

The moment of inertia of the arm 21 about the pivot 28 is adjustable toobtain the desired engagement with the tape so that excessive vibrationof the contact 6 is prevented. The tension on the springs is alsoadjustable to cooperate with the moment of inertia as determined by theweight and at the same time regulate Ithe pressure of the contact 6 uponthe tape 4 and give the arm 521 a natural period most suitable forrecording the impressed signals.

If it is not desired to reproduce the recordings immediately after therecording is made by means or the recording mechanism, the tape 4 may bepassed directly to the constant speed .contact rollers 6 and 9 or overany suitable intermediate roller or guide between the recordingmechanism and the constant speed rollers 8 and 9.

In the construction shown in Fig. 1, however, the tape is shown aspassing through a reproducing mechanism C about to be described.

The reproducing mechanism shown in Fig. 1 consists of a concentratedlament lamp 55 and lens system 56 of the type used in sound filmreproductionjor producing a narrow slot image. The lamp and lens systemis used in my apparatus for concentrating the light on the tape 4 as itpasses over the Vexposure guide 1 through a slotted aperture 51 in thewall of the compartment.

The light is reflected from the tape 4 into a suitable light sensitivedevice such for example as a photo-electric cell 58, the resistance ofwhich is thereby caused to vary in response to the variations inintensity of the'reected light, due to indices or markings recorded uponthe tape 4. The Variations in resistance are translated into voltagevariations and amplied in the usual manner 'by a suitable amplifierindicated at 59. The lamp 55 is supplied with current in any suitablemanner such as by the battery 55a or by a transformer and lter orrectier. The lamp 55 and lens system 56 and the photo-electric cell arepreferably enclosed in suitable compartments so that unwanted light doesnot reach the tape 4 orthe photo-electric cell. l Y

While I have shown a well known type of slot image lens system forprojecting a band of light on the tape 4, it is to be understood thatany means of projecting a concentrated band of light on the tape 4 maybe used, such as a plate having a narrow aperture through which thelight passes, and placed directly in front of the tape, and between itand the light source and a light sensitive device responsive tovariations in intensity of light, such as a suitable photo cell. Ineither case the light projected on the tape preferably should be a bandat least as narrow as the finest width of the finest division recordedon the tape 4 in order to secure faithful reproduction of the highestfrequency recorded.

The frequencies which can be reproduced depend upon the speed of thetape, the clearness of the definition and width of the recorded indices,

' leads 62 and 63 and flexible connections 64 and 65 to the recordingamplifier output. The flexible connections slidingly engage the rollers.The roller 6| is mounted for rotation on the fixed pivot 66 which ismounted on `an insulating frame 61. The roller 88 is mounted forrotation on the contact arm 68 which is rotatably mounted on the pivot69, which is similarly mounted on the insulating frame 61. Adjustablemechanism is provided for swinging the arm about the pivot 69 to move ittoward or away from the tape 4 to adjust the pressure of the rollersupon the tape. The mechanism for making this adjustment comprises ascrew 18 which passes through the threaded aperture in the stud 1|carried by the frame. The screw 10 is provided with a collar 12 so thatthe compression spring 13 is held between the screw and the arm -68 tomaintain a yielding pressure, whereby irregularities in the tape 4 canbe compensated for. The arm 68 has a cut out portion to engage spring13. In order to move the roller 68 away from tape 4 a tension spring 15is carriedY between arm 68 and stud 16.

In this construction Wear on the contacts isl largely eliminated due tothe fact that the tape passes between rollers and causes the rollers torotate,and sliding friction between the rollers is thereby eliminated.

The rollers are of small diameter and presentv substantially a linecontact to the tape 4 so that the fine markings due to rapidly varyingelectrical impulses may b`e recorded on the` tape.

Figs. 6, '1 and 8 show still another modified form of recordingmechanism. In this form the tape 4passes over a fixed contact 80. Thecontact member 8l is attached to a movable arm 82 which' is adapted tobe raised and lowered by the action of the moving member 83 of aphonograph pickup or recorder 84 which is adjustably secured to thelever arm 85 by screw 86 engaging with the back of the recorder housing.A tension spring 81 is attached to lever 85 at one en d and to asecuring means 88 at the other end. An adjusting screw 89 workingthrough stud 98 carries a conn ector 9| which is fastened to lever arm85 and engages screw `89. An adjusting 'nut 92 is provided to hold thescrew in adj usted position.

The spring 81 and the screw 89 provide a means for accuratelypositioning the arm 85 so that the movable contact member 8| is heldinthe desiredposition with reference to the tape 4. The lever arm 85 isrotatively connected to insulating panel 93 by shaft 94. Fixed contact88, stud 98,

and spring holder 88 are also mounted to this insulating panel. iThecurrent from a recording amplifier' is lead into the actuatingwinding of the phonographA recorder or pick-up through the terminalleads 95 and 96.

One terminal of a source of direct current potential, such as a batteryor generator, is connected to lead 91 and connected to arm 82 through avery flexible lead' 98.Y The other terminal of such source is connectedto fixed contact 8 8 through lead 99. The fixed contact 88 is insulatedfrom the rest of the circuit and is similar in forml and function to thecontact 5, Fig. l. AThe contact member 8| is secured to the arm 82l andis preferably thin for sharply defining the marks or cially suitable forrecording the ordinary code signals, or any signal not requiringexceedingly fine graduations of frequency or tone.

While I have shown, for convenience, the mounting of considerable of thevarious recording mechanisms disclosed in this application on aninsulating panel, itis to be understood that they may be suitablymounted on a supporting frame and electrically insulated therefrom inany suitable manner.

Fig. 2 shows diagrammatically an electrical system adapted for recordingor reproducing in connection with my invention. A microphone amplifieras illustrated has a pick-up means for use when recording sound waves.In the direct' coupled amplifier illustrated VT| is a. three elementthermionic valve` of the heater type cornmonly having an amplificationfactor .'1 to l0. VT2 is a four element thermionic valve of the heatertype having a screened plate. VT3 is an output thermionic valve of largecapacity. The grid |85 of VI2 is directly connected to the plate |06 ofVTI and the grid |81 of VTS is directly connected to the plate |85aofV-'I2. The plate |88 of VI3 isA connected through the milliammeter |89to the terminal 48.

The circuit shown in this figure is that of a direct connected amplifierdiffering from others of this type mainly in the values of theresistance and capacities used, which values are given below by way ofexample. ance having a value of 25,000 ohms. Variable resistance I2,inseries with resistance I I3, has a maximum value of about 500,000ohms. ||3 is a fixed resistance of 500,000 ohms and is connected at oneend to resistance ||2 and at the other end between resistances ||1 and||8. ||4 is a grid biasing resistance for the valve'v VT2 and has avalue of 25,000 ohms. ||5 is a. potentiometer having a resistance ofabout 400 ohms. ||6 is a resistance of 5,000 ohms and resistance ||1hasa value of 15,800 ohms. Resistance I8 has a value of 10,000 ohms andresistance ||9 has a value of about 250,000 ohms,and may be variable.Condensers |28 and |2| have a value of about a half a micro-farad each.Condensers |22 and |23 are filter condensers, and have values of onemicrois a grid biasing resistfarad and two micro-farad capacity,respectively.

sistances and condensers are those which I have found to give goodresults and these values may be departed from ,without affecting thespirit of the invention. A power transformer |21 has a primary windingadapted to the voltage and frequency of the circuit from which it isdesired to draw power. The transformer |21 is also provided with threelow tension windings lighting the filaments of the various valvesemployed in the amplifier and the high tension winding for use inconjunction with the rectifier valve |28 to provide high tension directcurrent for the various valves employed in the amplifier. The rectifiervalve |28 is a full wave rectifier which is used as a half waverectifier by having its plates connected as shown in Fig. 2 for thepurpose of obtaining an increased output. The choke |29 should have avalue of about 30 henries inductances. Terminal |30 is provided so thatif desired, a loud speaker for direct monitoring purposes may beconnected between the terminal |38 and the terminal 46.

The points |3|. |3|, ISI indicated as grounded in Fig. 2 are connectedto each other and this may be conveniently accomplished by connectinglthem to the metal frame or a suitable ground.

In Fig. 9 is shown, diagrammaticailyy another system for supplying thevarying electrical impulses to the recording contacts MD, SM betweenwhich the tape 4 passes. These contacts are simlar to those heretoforedescribed.

In this form the signal to be recorded is supplied to the tube VT4,through audio amplifying ltransformer |42. The current passes from thebattery |43, through the filament of the tube VT4, and is regulated inamount by the resistance |44. The battery |45 furnishes a suitablenegative potential to the control member of the tube VT4 through thesecondary Ywinding of the audio frequency transformer M2. The potentialof the control member relative to the lament can be adjusted bypotentiometer Ia. The battery |46 supplies the plate current to the tubeVT4 through the contact members |40 and itl, through the miliammeter'|41 to the plate of the tube VT4.

follows:

Incoming signals are impressed upon the control member of the tube VT4by means of the audio frequency transformer or other means whereby thecurrent in the plate circuit is caused to vary in accordance with thesesignals. The variations in-the current passing through the tape at thecontacts I G and |4| cause marks or indices of different intensities tobe formed upon the tape by the action of the current, proportional inintensity and frequency to the impressedA signals.

The simplified form shown in Fig. 9 is especially convenient` forrecording telegraph messages, wherein the familiar dot and dash systemis used.

For recording purposes a record receiving element is desired which isccmposed of a material which will carry chemicals reactive to thepassage of electric current, and on which indices can be progressivelyrecorded. A convenient form for such an element is that of a band ortape.

It is desirable for the band or tape to have a smooth surface so thatthe movable electrode may readily maintain substantially uniformrelation thereto. As an example cf such material, I have found lthat a.rag paper having a smooth calendered surface, cr a sulphite paper notheavily lled or glazed, may be used.

The operation of this device is as of a particular voice.

' than for voice.

The tape is treated or impregnated, preferably with a. chemical solutionwhich will react, upon the passage of an electric current betweensuitable 'contact electrodes, to produce a sexies of marks or indices,such as dots or lines, corresponding to the frequency and intensity ofthe electric current impressed on the tape. A fragment of tape 4 withsuch marks or indices thereon is shown in Fig. 12.

Preferably, it is desired to use such a chemical solution as will give aseries of colored lines or dots, so that these lines or dots may bereadily reproduced by means of a photo cell, or in any other manner.

I have found that a suitable bath for treating the tape may be made with100 parts of water, parts of potassium ferro cyanide and 1 part ofpotassium cyanide.

Theftape may be pressed to remove the excessive moisture, or dried, orotherwise conditioned. It is more convenient for use and for handling tohave in the tape'only a low moisture content. I have found that themoisture content of the tape may vary over wide limits, from the almostnormal content of paper of about 10% to a nearly saturated condition.However, as stated above, for practical purposes the low moisturecontent is more desirable.

The use of potassium ferro cyanide and potassium cyanide in theimpregnating bath gives a tape upon which a clear, colored series ofindices, such as dots or lines, may be formed by subjecting the tape toa varying electric current. The potassium cyanide seems to be of benefitin the solution, in that the dots or lines appear to be more sharp anddefined when this is used, and this may be because the potassium cyanideacts as a solvent for minute portions of the decomposition product atthe edges of the dots or lines formed by the' action of the electriccurrent on or roll and, as shown in Fig. 1, fed from the reel i 2` overthe xed contact 5 and under the movable contact 6. The speed .of feedingthe tape is prefv For example, I have found that in recording 'v voicesignals I can use speeds as low as 41/2 (inches) per second, but it isusually preferable, for the best results, to use somewhat' higher speedsto bring out the peculiar characteristics For recording music, thespeeds should preferably be somewhat higher I have produced satisfactorymusic recordings with speeds no higher than 12 inches to 14 inchesperrsecond.

Itis to be noted, however, that the optimum speed of recording isdependent, not only upon the speed and intensity of the current, and thereaction speed of the chemicals used to treat the tape, but also uponthe quality of the results which it is desired to obtain.

Also, it may be noted that heat' is liberated at the contact point whenrecording, and it may be that this liberation of heat facilitatestherecording. The heating may be regulated by varyingthe signal intensity,the amplier controls or the output impedance of the amplifier or byother well known means.

In operation, the position of the weight 29 (Fig. 1) on the recordingarm 21 and the tension of the springs 32 and 38 are adjusted to give thearm 21 a natural period, which will tend to cause the contact 6 tofollow smoothly any minute irregularities in the surface of the tape andprevent the arm from following an external impulse and responding toforced vibrations. An electric current ows from the rectifier |28through the choke |29 (Fig. 2) to terminal 41(Figs. 1 and-2) i rectifier|28.

When no signal is acting on the. apparatus, the grid of VTI issuiciently negative with respect to the cathode so that the currentflowing in the plate circuit is small. The drop through resistances H2and ||3 is, therefore, small, and grid |05 of VT2 is sufficientlypositive so that a larger than normal current flows through the plate`|05e. 'I'he drop through resistance ||9 is, therefore, larger thannormal, and the grid |01 of VT3 is more negative than normal withrespect to the filament |34 and current owingto the plate |08, themilliamrneter |09, terminal 46, and the moving contact and tape, issmall. If the grid of VTI is made more positive by an incoming signal,or otherwise, the current in the plate circuit of VTI willincrease, thecurrent in the plate circuit of VT2 will decrease, and the currentthrough the plate circuit of VT3 and the treated tape will increase,causing a line on the tape, the width of which is proportional to thetime of duration of the signal or positive condition of the grid of VTI,and the intensity of which is proportional to the intensity of thecurrent through the tape. Thus, a rapidly varying electro-motive force,such as that resulting from a succession of sound waves applied to themicrophone '|35 (Fig. 2), results in producing a series of fine indicesor marks, such as lines, on the tape, the nature or character andfrequency of which correspond to the volume and frequency of thesuccession of sound waves which are being recorded.

The signals impressed upon thegrid |01 of the vacuumrw tube VT3 are of4suflicient intensity to swing the gridpotential to a positive value,

causing marked variations in the plate current of the tube. Themilliammeter |09 indicates these variations and furnishes a criterion ofthe character of the record being made upon the tape. It sometimeshappens that the tape has what might be termed a.v threshold value ofcurrent, so that a current of sufficient intensity must be applied tothe tape before any record is made. The normal direct current Vcomponentof the plate current of the valve VT3 is usually sulcient for thispurpose, but in case a larger direct current component is required, theplate current of the valve VT3 may be increased by connecting aresistance, as |32, between the center tap of the filament transformerfor VT3 and the groun side |3| of the high tension winding.

Although I have shown in Fig. 2 a. direct con.-

nected amplifier operated from an alternating current source, it is tobe understood that this invention is not limited to the type ofamplifier shown, for example, a transformer coupled amplifier or aresistance capacity coupled amplifier operated either from drybatteries, accumulators, or by proper rectifying means from analternating current source may be employed.

In order to disclose the working of my invention I have shown anordinary carbon microphone transmitter |35 connected, by means of itstransformer and battery |36, to terminals |31 and |38 of the amplifiershown in Fig. 2. It is to be understood, however, that a radio receivingset or other devices for transforming light waves, sound waves or'othermechanical vibrations into electrical energy may be utilized in place ofthe transmitter microphone.

It will be seen that I have shown a. mechanism making it possible torecord on a. tape and then immediately reproduce the record formonitoring or other purposes. It will also be seen that the reproducingapparatus can be operated without a recording mechanism to reproducerecordings that have already been made, since the recordings on the tapeare of such a nature that the tape can be keptfor long periods of timebefore being reproduced without deterioration of the record.

Furthermore, my invention furnishes a method of introducing a delaybetween the production of speech or music and the reproduction of thesame. For instance, if -it be desired to reproduce the speech or musicshortly after its production, and

the length of tape between the recording mechanism and the reproducingmechanism is 14 inches and the tape is running at the rate of 14 inchesper second, a delay of one second between the recording and thereproduction of the sound will occur. This delay will occur while thetape is traveling from the recording point to the reproducing point.This time obviously may be varied by changing the distance between therecording and reproducing points to obtain. the desired amount of delay.f

There are many interesting and useful applications o1 this: .forinstance, such as when a person desired to play a phrase of music, orspeak va few sentences, and have that phrase or speech reproduced assoon as he-is through playing or speaking, in order that he may obtainan idea of how it sounds and what the resultant effect is; or when adelay is desired as in two-waywireless communication, to allow time forcutting oli" the transmitter and cutting in the receiver withoutapparent interruption in the communication.

Afurther advantage of this device lies in its ability to render signalsor messages unintelligible in transmission. This may be accomplishedeither by running the tape with indices recorded thereon, backwardthrough the reproducing devicey for transmission, receiving andrecording on another tape, and running that tape backward through areproducing device for intelligible reception of the signals asmessages, or by running the tape through the reproducing device andtransmitter at a rate' of speed sufliciently high to preventintelligible reception and then receiving and recording at a rate ofspeed corresponding tothe transmitting speedgand reproducing the messageby running the tape at a lower rate of speed.

It will be noted that an important advantage to be substantially dry,and can, therefore, be readily handled in' reeling and storing, and heldin this condition Without the necessity of meistening the tapeimmediately before recording.

It will also be seen that after the recording is made the moisturecontent is substantially immaterial, an'd that the tape may be wound onreels, rolls, or the like, and stored for long periods of time until itis desired to use it for'reproduction.

Also, it will be seen that a relatively narrow tape, such as one-halfinch, may be used, and 1 that a large amount of recording Will berelatively light and may be easilystored and transported. It may benoted, however, that a tape sufficiently wide to have impressed thereona plurality of series of indices by passing the tape successive timesthrough the recording mechanism may be used. l

It will also be seen that, instead of treating or coating a tape withchemical compounds to enable it to receive the marks or indices, suchcompounds may be incorporated in the paper or other material from whichthe tape is made during the manufacture ofthe tape.

Furthermore, it 'is to be understood that the particular forms ofapparatus shown and de scribed, and the particular procedure set forth,are presented for purposes of explanation and illustration and thatvarious modifications of said apparatus and procedure can be madewithout departing from my invention as defined in the appended claims.

What I claim is:

1. Apparatus for recording electrical impulses, which comprises, incombination, a movable tape carrying a substance adapted to react to thepassage of an electric current therethrough, a thermionic valve orvalves, means for applying varying voltages to the thermionic valve orvalves, means coacting with the movable tape forimpressing the resultantvarying electrical output of the thermionic valve or valves thereon,said means comprising electrodes, one of which is a thin blade disposedtransversely of the tape, and means for moving said tape, wherebysuccessive lines are produced on the tape transversely thereof, eachline being produced by a single electrical pulsation.

2. Apparatus for recording and reproducing` Soundwaves in the audiblerange which comprises, in combination, a movable tape carrying asubstance adapted to react to the action of an electric current, athermionic valve, means for receiving sound waves and transforming theminto electrical impulses and for subjecting the control member of saidthermionic value to sai-d impulses, means for moving the tape, means for'impressing the electrical output of said valve on successive portionsof the tape to form a series ci indices, means .for impinging a lightbeam upon indices of the moving tape and reflecting the light into alight sensitive device of a type. ca` pable of transformng lightvariations to electrical impulses, and means for transforming theseelecvariations into electrical impulses, and means for transformingthese electrical impulses into high frequency sound waves, whereby vocaland musi- I cal sounds may be accurately recorded and reproduced.

4. Apparatus for recording and reproducing sound Waves in the highfrequency audible range, l

which comprises in combination,'a movable tape carrying a substanceadapted to react to the effect of electric current thereon, a thermionicvalve, means for receiving such sound waves and transforming them intoelectrical impulses, means for applying said electrical impulses to thethermionic valve, electrodes disposed transversely of the'tape onopposite sides of the tape connected to receive the resultant varyingelectrical output of the thermionic valve, means for moving said tapebetween said electrodes whereby indices are iii produced on successiveportions of the tape, one of said electrodes comprising a thin recordingblade disposed transversely of the tape to produce indices of relativelyfine gradations corresponding to the basic frequencies and harmonics ofthe i vocal and musical sounds being recorded and reproduced, means forimpinging light beams upon said indices of the moving tape and reectingthe light into a light-sensitive device of the type capable oftransforming light variations into elecl trical impulses, and means fortransforming these electrical impulses into high frequency sound waveswhereby vocal and musical sounds may be accurately recorded andreproduced.

5. Apparatus for recording and reproducing sound waves in the audiblerange which comprises, in combination,v a movable tape carrying asubstance adapted to react to the action of an electric current, athermionic valve, means for receiving sound waves and'transforming thema into electrical impulses and for subjecting the control member of saidthermionic valve to said impulses, means for moving the, tape and meansfor impressing the electrical output of said valve on successiveportions of the tape in the form of transverse lines of materiallygreater length than Width, and means controlled 'by said tape forproducing electrical impulses corresponding to those impressed on thetape and for transforming these electrical impulses into sound wavescorresponding to those producing the electrical impulses previouslyimpressed on the tape.

6. A method of recording electricalimpulses upon a tape carrying asubstance adapted to react to the effect of electric current thereon,which consists in applying varying volt-ages to a thermionic valve orvalves, impressing the resultant varying electrical output of said valveor valves on successive portions of said tape to form ne transverselines proportional in spacing and intensity to the variation of thecurrent in frequency and intensity while moving the tape at asubstantially uniform speed and thereby causing successive portions ofthe moving tape to receive the eiiect of the electrical impulsesimpressed thereon and to be differentiated from other portions of thetape.

7. A method of recording electrical impulses on a tape 'carrying asubstance adapted to react to the effect of electric current thereon,which consists in applying varyng voltages to a thermionic valve orvalves, feeding the tape at a substantially uniform speed in properrelation to electrical contacts to receive electrical impulsestherefrom, impressing the resultant varying electrical output of saidvalve or valves on said tape to form successive fine transverse lines ofmaterially greater length than width and proportional in spacing andintensity to the varying electrical output of said valve or valves whilethe tape is moving relative to the contacts, and thereby causingportions of the moving tape to receive the effect of the electricalimpulses impressed thereon and to be differentiated from other portionsof the tape.

8. A method of reproducing mechanical vibrations, which consists intransforming-said vibrations into electrical impulses, applying theelectrical impulses to a thermicnc valve, impressing the resultantvarying electrical output of said valve on portions of a tape, carryinga substance adapted to react to the effect of electric current thereon,to cause successive indices to be produced on said tape, causing a lightbeam to im` pinge upon said indices on the moving tape and to bereflected into a light sensitive device of a type capable oftransforming light variations into electrical impulses, and transformingthese electrical impulses into mechanical vibrations ofk substantiallythe same frequency and intensity as those originally transformed intoelectrical impulses. Y

9. A method of reproducing mechanical vibrations, which consists intransforming said vibrations into electrical impulses, applying theelectrical impulses to a thermionic valve, moving at a uniform rate atape carrying a substance adapted to react to the effect of electriccurrent, impressing the resultant varying electrical output of saidvalve on portions of said tape, to cause successive transverse lines tobe produced on said tape, causing a light beam to impinge upon saidlines on the moving tape and to be reflected into a photo cell, andtransforming the vresulting electrical vibrations of said cell intomechanical vibrations.

10. A method of reproducing mechanical vibrations, which consists intransforming said vibrations into electrical impulses, applying theelectrical impulses to a thermionic valve, moving at a uniform rate atape carrying a substance adapted to react to the effect of electriccurrent, impressing the resultant varying electrical output of saidvalve on portions of said tape, to cause l successive indices to beproduced on said tapeg` and reproducing from said indices the recordedsignal after a predetermined lapse-of time.

11. A method of reproducing sound vibrations,

which consists in transforming sound vibrations into electricalimpulses, impressing the electrical impulses on a moving tape carrying asubstance ting mechanical vibrations, such as code signals or soundwaves, and maintaining them secret durspeed, and transmitting theelectrical impulses so produced to a second recording apparatus similarto the first and having a tape moving at a relatively high rate of ispeed corresponding to that of the first tape and reproducing themechanical vibrations from the second tape at a speed corresponding tothe original recording speed.

13. Apparatus for recording and reproducing electrical impulses whichcomprises, in combinatio/n, a movable tape carrying a substance to reactto the action of an electrical current thereon, a pair of rollersdisposed on opposite -sides of the tape and con cted to receive theelectrical impulses, means for o'ving the tape between said rollerswhereby transverse lines of greater length than width are producedonsuccessive portions of the tape, means for impinging a beam of lightupon said lines of said moving tape and causing the light coming fromsaid tape to pass into a light sensitive device of the type capable oftransforming light variations into electrical'impulses.

14. Apparatus for recording sound waves which comprises, in combination,a movable tape carrying a substance adapted to react to the effect ofelectric current thereon, a thermionic valve,

means for receiving such sound waves and transforming them intoelectrical impulses, means for applying the electrical impulses to thethermionic valve, electrodes disposed on oppositel sides of the tape,and connected to receive the resultant varying electrical output of thethermionic valve, one Vt:

of the electrodes including a .thin blade mounted transversely of thetape, said electrode being mounted for yielding movement relative to thetape so that the electrode `may have a natural period most suitable forrecording the impressed signals, whereby transverse indices ofrelatively fine gradations corresponding to the basic frequencies andharmonics of the sounds being recorded are produced on the tape.

15. The method of recording and reproducing a varying electric current,which consists in impregnating an opaque record member with a chemicalwhich changes its color on the passage of electricity therethrough,passing said current through an amplifying system whereby the variationsin said current are sensibly amplified, passing said opaque recordbetween electrodes connected to said amplifier whereby said amplified rcurrent is passed through said record and discolors it alongafpredetermined course in a manner corresponding to the variations insaid current, impinging a constant beam of light on said opaque recordalong said predetermined course, causing reflected lightfrom said recordalong said predetermined course to pass into a photo cell, andamplifying the electric output of said photo cell, whereby a varyingelectric current whose variations correspond in frequency and intensitywith the original electric current is obtained. i

16. Apparatus for recording electrical impulses which comprises, incombination, a tape carrying a substance adapted to react to the actionof an electric current, said tape having such a relatively low moisturecontent that it appears dry, a thermionic valve, means for moving thetape,

means for impressing the output of the valve on successive portions ofthe tape to form transverse lines of materially greater length thanwidth on said tape, said lines varying in spacing and intensityirl-proportion to the impulses impressed upon the valve.

17. A tape of the character on which sharply contrasting lines, varyingin spacing and intensity, may be produced under the influence of arapidly varying electric current, which comprises a paper tapeimpregnated with a solution of a chemical capable of change of colorupon the passage of an electric current through the chemical, themoisture content of the tape being such that the tape appears dry butcontains more than 10% moisture.

18. Apparatus for recording and reproducing sound waves in the audiblerange, which comprises, in combination, a movable tape carrying asubstance adapted to change in color from the eiect of electric currentthereon, means for receiving such sound waves and transforming them intoelectrical impulses, an electrical amplifying system including one ormore thermionic valves, means for applying said electrical impulses -tothe amplifying system, electrodes disposed transversely of the tape onopposite sides thereof connected to receive the resultant varyingelectrical output of the amplifying system, means for moving said tapebetween said electrodes whereby discolorations are produced onsuccessive portions of the tape transversely thereof of materiallygreater length than width and varying in frequency and intensity withthe variations in frequency and intensity of the original sound, meansfor impinging a light beam upon said indices'of the moving tape, andmeans for passing the resultant varying reflectedlight into a lightsensitive device of the type capable of transforming light variationsinto electrical impulses, and means for transforming these electricalimpulses into sound Waves, whereby vocal and musical sounds may beaccurately recorded and reproduced.

19. Apparatus for recording electrical impulses comprising incombination, a tape carrying a substance adapted to react to the passageof electrical current therethrough, means for moving said tape, aplurality of thermionic valves directly coupled in cascade, a source ofhigh tension direct current, the majority of which current must passthrough said tape and last of said thermionic valves in cascade to theother valves directly coupled to said last valv`emeans for impressingvarying electrical impulses on the control member of the first of saidthermionic valves in cascade, whereby successive indices in the form ofdistinct transverse lines are formed on said tape which correspond inspacing and intensity proportionally to the frequency and intensity ofthe impressed electrical impulses.

' consists in applying varying electrical impulses to a thermionicValve, applying the output of the valve to an electro-magnetic membercapable of vibrating in response to varying electrical impulses andhaving a thin recording blade electrode, feeding 'thetape at asubstantially uniform speed over a stationary electrode spaced from thefirst electrode, and applying direct current across said electrodes andthrough the tape disposed therebetween, whereby the eect of theelectrical impulses impressed upon the valve are impressed on the tapein the form of transverse lines of greater length than Width.

2l. An opaque paper tape impregnated with a chemical and having indicesimpressed thereon as the result of the direct application to said tapeof electrical impulses, said indices comprising visual, successive,transverse lines relatively narrow in width and of materially greaterlength than Width, and also being proportional in spacing and intensityto said electrical impulses.

MERLE DUsToN.

